The book also makes reference to claims that Cowen’s disastrous final cabinet reshuffle was carried out "within the sanctuary of the Dail (parliament) bar."

Written by journalists Bruce Arnold and Jason O’Toole, ‘Fianna Fail, The End of the Party’ also claims that Cowen was surrounded by "drinking buddies" in the parliament building bar who would "fetch him pints and fill him up."

Senior sources within the Fianna Fail movement revealed that Lenihan’s career was "stymied by the fact that he was not part of the infamous bar lobby - he didn’t buy pints for Brian Cowen."

The authors say that the relationship between Cowen and Lenihan soured as the economy collapsed and the hard drinking culture took over the Fianna Fail hierarchy.

They also write that the decision makers would retire to a small cottage at the government owned Farmleigh Estate "to have some more pints after last orders at the Dail bar."

Ministers are also quoted in the book as saying of Cowen "Jesus... he certainly drank an awful lot. Everybody thought that when he became Taoiseach he’d stop, but he actually didn’t." Other ministers rejected the claim.

O’Rourke, Lenihan’s aunt, also commented on Cowen’s drinking. “I don’t think Cowen went on benders, I just think he drank steadily - not during the day, no, no, no, in the evening time when he’d be finished in the Dail.”

The book also states that Lenihan urged Cowen to call a general election in September 2010 because he feared Ireland was going to be bullied into accepting a bailout. Cowen told Lenihan: “Not to worry we will muddle through.” Just weeks later the IMF loan was forced on the FF led government.

The book also outlines Lenihan’s battle with cancer as his relationship with Cowen deteriorated.